Research Programs from BAA - Physics

6.0 Overview

The objective of the ARO Physics Division is to develop forefront concepts and approaches, particularly exploiting atomic-scale and quantum phenomena, which will in the long-term have revolutionary consequences for Army capabilities, while in the nearer-term providing for existing Army needs. In support of this goal, the interests of the Physics Division are primarily in the following areas: condensed matter physics, quantum information science, atomic and molecular physics, and optics and fields. There is little direct interest in relativity and gravitation, cosmology, elementary particles and fields, nuclear physics, astronomy, or astrophysics, since they generally have little impact on the areas of Army needs. Nevertheless, the possible relevance of topics within these other physics disciplines is not absolutely discounted, and discussions of potential exceptions are welcome.

The disciplinary boundaries of ARO are not sharply drawn, as shown by the joint support of a number of efforts by the Physics Division and other ARO Divisions. In addition, it is not necessary that a potential investigator be associated with a physics department to receive support from the ARO Physics Division.

6.1 Condensed Matter Physics

Condensed Matter Physics (CMP) is a foundational science enabling fundamental Army technologies in areas such as information processing, communications, sensors, optical components, electronics, optoelectronics, night vision, seekers, countermeasures, and many others. Technologies such as these would not exist today, at least not as we know them, without visionary research in the field of CMP. The ARO CMP Program strives to continue this level of impact by looking beyond the current understanding of natural and designed condensed matter, to lay a foundation for revolutionary technology development for next generation and future generations of warfighters.

6.1.1 Strong Correlations and Novel Quantum Phases of Matter

Understanding, predicting, and experimentally demonstrating novel phases of matter in strongly correlated systems will lay a foundation for new technology paradigms for applications ranging from information processing to sensing to novel functional materials. Interest primarily involves strong correlations of electrons, but those of other particles or excitations are not excluded. This thrust predominantly emphasizes complex oxide heterostructures as a material system in which the discovery, design and control of electronic correlations may be possible. The program seeks to foster novel experimental and theoretical research targeting the discovery and rational design of new quantum phases of matter, along with exploring how excitations within these phases can be probed and controlled.

6.1.2 Topological Electronic Phases in Condensed Matter

Novel quantum phases of electronic matter can also exist apart from strong correlations as recent developments in topological insulators has demonstrated. This thrust seeks to expand the physics embodied in the topology of the electronic structure, including the role of strong correlations and other influences, theoretically predicted or not. Interest emphasizes experimental studies but not to the exclusion of theoretical efforts. Studies in physics and physics-enabling chemistry, such as bulk crystal growth, heteroepitaxial growth modes, and surface chemistry are also of interest.

6.1.3 Unique Instrumentation Development

Advanced studies of CMP phenomena often require unique experimental techniques with tools that are not readily available. The construction and demonstration of new methods for probing and controlling unique phenomena, especially in the studies of novel quantum phases of matter, is of particular interest. Further, structures and assemblies exhibiting unique CMP phenomena may require unique synthetic techniques, which might range from biological assembly to optical lattices. Establishing such techniques for the fabrication or simulation of condensed-matter systems are of interest when they provide access to novel quantum phenomena that are not otherwise readily obtainable.

6.2 Quantum Information Science

Quantum mechanics provides the opportunity to perform highly nonclassical operations that can result in beyond-classical capabilities in imaging, sensing and precision measurements, exponential speed-ups in computation, or ultrasecure transmittal of information. This program seeks to understand, control, and exploit such nonclassical phenomena for revolutionary advances beyond those possible with classical systems. An overarching interest is the exploration of small systems involving small numbers of entangled particles. There are three major areas of interest within this program.

6.2.1 Fundamental Studies

Experimental investigations of a fundamental nature of quantum phenomena, potentially useful for quantum information science, are of interest. Examples include coherence properties, decoherence mechanisms, decoherence mitigation, entanglement creation and measurement, nondestructive measurement, complex quantum state manipulation, and quantum feedback. An important objective is to ascertain the limits of our ability to create, control, and utilize quantum information in multiple quantum entities in the presence of noise. Of particular interest is the demonstration of the ability to manipulate quantum coherent states on time scales much faster than the decoherence time. Theoretical analyses of nonclassical phenomena may also be of interest if the work is strongly coupled to a specific experimental investigation, such as proof-of-concept demonstrations in atomic, molecular, and optical, as well as other systems.

6.2.2 Quantum Sensing, Imaging, and Metrology

This research area seeks to explore, develop, and demonstrate multiparticle coherent systems to enable beyond classical capabilities in imaging, sensing, and metrology. Central to this research area is the exploration of small systems involving a few entangled particles. Topics of interest in this research area include the discovery and exploration of (a) multiparticle quantum states advantageous for imaging, sensing, and metrology; (b) quantum circuits that operate on multiparticle quantum states to enable beyond—classical capabilities; and (c) methods for the readout of quantum states. Other research topics of interest include the theory to explore multiparticle quantum states useful for beyond classical capabilities; quantitative assessment of capabilities and comparison to classical systems; efficient state preparation, quantum circuits for processing these states as quantum bits; readout techniques, decoherence mitigation and error-correction for improved performance; supporting algorithms as a basis for processing circuits, connections between the solution of hard computational problems and overcoming classical limitations in imaging, sensing, and metrology, entanglement as a resource, suitable physical systems and key demonstration experiments.

6.2.3 Quantum Computation and Communication

Quantum computing and communication will entail the control and manipulation of quantum bits with high fidelity. The objective is the experimental demonstration of quantum logic performed on several quantum bits operating simultaneously, which would represent a significant advance toward that ultimate goal of tremendous speedup of computations. Demonstrations of quantum feedback and error correction for multiple quantum bit systems are also of interest. There is particular interest in developing quantum computation algorithms that efficiently solve classically hard problems and are useful for applications involving resource optimization, imaging, and the simulation of complex physical systems. Input/output interfaces for quantum computation to handle large amounts of classical data efficiently are of interest. The ability to transmit information through quantum entanglements distributed between spatially separated quantum entities has opened the possibility for an ultrasecure means of communication. Exploration of quantum communication of information based on distributed entanglements such as in quantum teleportation is of interest. In addition, the exploration of long-range quantum entanglements, entanglement transfer among different quantum systems, and long-term quantum memory are also of interest.

6.3 Atomic and Molecular Physics

Research efforts in the Atomic and Molecular Physics (AMP) Program will create fundamentally new capabilities for the Army, as well as providing the scientific underpinnings to enhance existing technologies. Topics of interest include (i) quantum degenerate atomic gases, both Bose and Fermi, their excitations and properties, including mixed species, mixed state, and molecular; (ii) matter-wave optics and matter-wave lasers; (iii) nonlinear atomic and molecular processes; (iv) quantum control; (v) novel forms and effects of coherence; and (vi) emerging areas. Cooling schemes for molecules are of importance for extending the range of systems that may be exploited. In addition, there is an interest in emerging areas of atomic, molecular, and optical (AMO) physics such as states of protected matter including but are not limited to topological phases, emergent lattices in quantum gases, opto-mechanical interfaces, nonequilibrium many body dynamics, and weak measurements. Research efforts within the AMP Program fall within two thrust areas: Molecular Physics and Generalizations of AMO Physics. It is anticipated that research efforts within these areas will lead to applications including novel materials, robust quantum devices, and novel fieldable quantum sensors.

6.3.1 Molecular Physics

The objective of this thrust is to broaden the scope of atomic physics into the molecular regime. Cooling, trapping, and reaching degeneracy of molecules fall into this scope, as well as the interactions between atomic neutrals and molecular ions. Coherent atomic-molecular superposition states, a novel form of matter, and molecules as well as atomic-molecular hybrids in lattices are other examples. The ability to use Feshbach resonances and otherwise tune interactions is also relevant here, both as a mechanism for ultracold molecule production and as a way to cross over from weak coupling to strong coupling regimes (e.g., in superfluidity). As previously alluded to, quantum fluids in an optical lattice provide yet more novelty, and offer a forum for investigating open questions in condensed-matter physics as well as explorations beyond. These include the study of dipolar and more complex molecules and mixed statistics systems in such lattices. The Molecular Physics thrust is distinguished from programs in the materials and chemical sciences. One distinguishing feature is its focus not on synthesis, but on the underlying mechanisms, such as electronic transport, magnetic response, coherence properties (or their use in molecule formation/selection), control, and/or linear and nonlinear optical properties. The systems of interest are well-defined molecules, generally small or of high symmetry, and their functionalized variants.

6.3.2 Generalizations of AMO Physics

The AMP Program also has a general interest in exploring fundamental atomic and molecular physics topics that may impact future Army capabilities. For example, cold atomic gases interfaced with opto-mechanics are the focus of fundamental research regarding the behavior of macroscopic quantum systems. Future "atomtronic" devices will need to be interfaced in a manner that allows them to perform in noisy environments and remain robust to outside perturbations. General issues of quantum coherence, quantum interference, nonequilibrium phenomena and quantum control as well as their numerous potential applications are also of interest.

6.4 Extreme Light

In order to achieve the kinds of breakthroughs previously described, this program focuses on research on extreme light, meaning the examination of light in the extreme limits, such as the shortest pulses attainable and the highest intensity fields attainable. Advances in these areas require theoretical and experimental research. For example, ultrashort pulsed lasers have now achieved intensities of 1022 W/cm2. Future applications of these pulses may include high-harmonic generation, nanolithography, micromachining, particle beam acceleration and control, and light filaments. In the near future, even higher intensities are expected. Theoretical and experimental research efforts are needed to describe and understand how matter behaves under these conditions—from single particle motion and radiation reaction to the effects in materials—and how to generate these pulses and use them effectively. Pulses as short as 80 attoseconds have been produced; the program seeks ways to make them shorter and to understand both the physics and applications of this form of radiation. Another example of extreme light is light filaments, where light and plasmas interact to form a new kind of energy propagation. The physics of the interactions as well as many yet to be discovered issues need to be understood; such as, how far can light filaments propagate and how much energy can they contain? Proposals for new areas of extreme light are also welcome.

6.4.1 Transformation Optics and Optical Metamaterials

This thrust pursues a fresh start in optics due to the existence of Negative Index Materials and more generally, optical metamaterials. In this area many conventional limits of optics can be broken in ways such as subwavelength imaging and superlensing related phenomena. It is timely to look at the quantum optics of such processes. This may establish true limits on capabilities and enable one to discover new phenomena not provided by the classical view. New forms of imaging using transformation optics or other novel imaging are also of interest. In general, any optical phenomena that can ultimately improve Army capabilities are sought.

6.4.2 Beyond Light

Any area in fundamental physics that may be exploited to achieve the previously described program goals is welcome. For example, modern theories of gravity as well as string theory predict, in addition to gravity, the existence of two other long-range fields. If these theories are correct in their predictions, this suggests applications where electromagnetism and optics fail, such as propagating through conducting media.